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Groundwater is in crisis.

Largely invisible, lightly regulated and used by 85% of California’s population and much of the state’s $45 billion agriculture industry, groundwater is a crucial reserve that helps stave off catastrophe during drought periods. A study done by researchers at Stanford concluded that after a century of unregulated use, California’s groundwater is in crisis, which carries profound economic, environmental, and infrastructure implications.

Over 6 million Californians rely solely or primarily on groundwater for their water supply. Contrary to a popular misconception of an underground river or lake, groundwater is found in the tiny spaces between sand and gravel. Generally, groundwater is used along surface water to meet the state’s needs, and in normal years groundwater providers 30 to 40% of the water supply. During this drought, statewide groundwater usage has doubled. Put another way, over 6 million Californians are living solely off of their savings account.

Using groundwater is as simple as drilling a well and pumping it out. There is no regulation because land ownership is pretty much a license to use groundwater. In the past, natural recharge was enough to balance the water that was pumped out. However, with powerful electric pumps, places like the Central Valley are withdrawing twice as much groundwater as nature is returning. If you withdraw money from your savings at a faster rate than you deposit new money, eventually you will have problems.

What are the solutions?

In the short term, Californians must control how much groundwater they withdraw from their savings account. Last September, Governor Jerry Brown signed into law the Sustainable Groundwater Management Act, which requires groundwater basins throughout California to be managed sustainably and gives the state the authority to step in if a specific groundwater management plan is deemed inadequate.

Of course, the long term problem is trying to meet the demands of households and the agriculture industry. The graphic below from Stanford compares the cost of popular water projects. Researchers found that the cost of recharge is cheaper than other water supply options and is a cheaper alternative to surface storage. Essentially, the most effective long term solution for water supply is to deposit money into California’s savings account. Source: Recharge: Groundwater’s Second Act groundwater

There are two ways in which water can get into the ground: naturally and artificially. Natural recharge is simply rain and streamflow that soaks into the ground into an aquifer. The problem is water is being withdrawn at twice the rate it’s being put in. The most common method of artificially replenishing the ground is the use of recharge ponds, which are constructed surface basins that allow water to slowly infiltrate the underground aquifer. a more energy-intensive method uses high pressure pumps to push the water underground. Of course, where will this water come from? Increasingly, alternative sources of water like recycled water, treated wastewater, stormwater, and agricultural runoff are all being used.

According to the Stanford report, California’s future water supply will best be met through a combination of groundwater recharge, improved groundwater management, water conservation, and water recycling. This is in contrast to the large surface water infrastructure projects that dominated the last century. Groundwater recharge is proven and cost effective, but the important question is, just how quickly can it help the state through this historic drought. In the short term, California will have to rely on smart management of its precious resource.